Bioefficacy of Bersama Abyssinica Extracts against Cowpea Beetle; Callosobruchus Maculatus in Storage

Abstract

Callosobruchus maculatus is a major pest of stored leguminous seed including black gram, green gram, cowpea and several other pulse grains. The development of eco-friendly pesticides has been a paramount in the prevention of post harvest loss. This study was therefore conducted to evaluate the efficacy of Bersama abyssinica extracts against Callosobruchus maculates (cowpea beetle). The bioassays were performed by two toxicity assays namely; extract seed dressing assay and direct toxicity by dipping where insecticidal activity was recorded by considering concentration and volume applied with mortality rate evoked. The result showed that both Bersama abyssinica methanolic and aqueous extracts caused insect mortality in a range of 60.25 ± 2.50% - 100 ± 0.00% at the rate of 0.5 - 2.0 mL/25g of cowpea seeds in direct toxicity by dipping assay.  They also induced mortality ranging from 76.67 ± 3.33% to 100.00 ± 0.00% in extract seed dressing toxicity assay where extracts were tested at concentration range of 0.02-0.06 g/ml. The overall results shows that Bersama abyssinica extracts could be effective insecticidal agents against Callosobruchus maculatus (cowpea beetle) and thus improves food and nutritional security in cowpea seeds.